Figure 6.

Optical Inhibition of DRN DA Neurons Reduces Social Preference Only Following Isolation

(A) Group-housed TH::Cre mice expressing NpHR (upper panels) or eYFP (lower panels) in the DRN, in a Cre-dependent manner, were assessed in the three-chamber sociability task. Time spent in the social zone across the first 5 min of the task (inset shows total time) and (B) the social:non-social ratio. Optical inhibition did not produce a detectable difference in the total time spent in the social zone (NpHR, inset, paired t test: t₁₂ = 0.1778 p = 0.8619, n = 13; eYFP: t₉ = 0.1788, p = 0.8621, n = 10) or the social:non-social ratio (NpHR, paired t test: t₁₂ = 0.2414, p = 0.8133, n = 13; eYFP: t₉ = 1.293, p = 0.2282, n = 10).

(C) Mice were isolated from their cagemates for 24 hr and then tested for sociability with optical inhibition. Time spent in the social zone by NpHR- and eYFP-expressing mice across the first 5 min (inset shows total time) and social:non-social ratio following isolation. NpHR-expressing mice spent a significantly lower proportion of time in the social zone after 24 hr of isolation compared with eYFP-expressing mice (social:non-social ratio, unpaired t test: t₁₆ = 2.236, ^∗p = 0.0400, n = 7 eYFP, 11 NpHR).

(D) Representative spatial heat maps showing the location of an NpHR- (upper panels) and eYFP-expressing mouse (lower panels) in the first 5 min of the task, when group-housed and following 24 hr of isolation.

(E) Time spent in the social zone and social:non-social ratio of mice tested with photoinhibition while group-housed and following social isolation. Photoinhibition in NpHR-expressing mice resulted in a significant reduction in time spent in the social zone (paired t test: t₁₀ = 2.740, ^∗p = 0.0208, n = 11) and social:non-social ratio (paired t test: t₁₀ = 2.239, p = ^∗0.0491, n = 11) following social isolation, compared to when group-housed.

Data are represented as mean ± SEM. See also Figure S6.